This invention relates to ball slides, and more particularly to an improved ball slide which permits extended travel of the female slide member relative to the supporting male member, as compared to conventional ball slides.
Conventional ball slides normally comprise a rectangularly shaped male or base member, and an inverted, generally U-shaped female section or slide member, which is supported on two sets of rollers or ball bearings for movement longitudinally of the base member. In a ball slide such as shown for example in U.S. Pat. No. 3,113,807, these two sets of bearings travel in two, laterally spaced raceways, which are located between a first pair of longitudinally extending grooves that are formed on the inside surfaces of the two furcations of the U-shaped slide member, and a second pair of longitudinally extending grooves that are formed in the opposed sides of the rectangular base member each to register with one of the grooves of the first pair. Each such groove contains a pair of spaced, parallel longitudinally extending bearing rods which define one side of a respective raceway. When ball bearings are employed, each set thereof is mounted for rotation in a conventional keeper plate or retainer, which is mounted for limited reciprocation between opposite ends of the slide member as the latter reciprocates on the base member.
Heretofore with ball slides of the type described it has been customary for opposite sides of each raceway, and the associated portions of the ball or roller bearing systems, to be similar or essentially mirror images one of the other. With this construction, as the saddle or slide member moves in one direction relative to the base member, each set of roller or ball bearings roll at opposite sides thereof along the associated pairs of bearing rods. This causes the two rods at one side of a raceway to engage or track against each ball bearing along the same circumferential paths as the two rods at the opposite side of the raceway. As a consequence, upon movement of one of the slide and base members relative to the other, the travel of each such member relative to the ball retainers will be the same. Moreover, the maximum length of travel of a member in one direction will be twice the travel of the retainers. Consequently, to obtain extra travel of the sliding or saddle member, it heretofore has been customary to lengthen the slide member to permit greater travel of the retainers or keepers relative to the slide member, or alternatively to shorten the ball keepers The disadvantage of shortening the ball keeper is that the ball bearing systems are correspondingly shortened, and thus the stability of the ball slide may be reduced. On the other hand, lengthening the slide member often precludes use of the slide in applications where space restrictions require a short slide member.
It is an object of this invention, therefore, to provide an improved ball slide of the type described which permits extended travel of the sliding member or saddle relative to the base plate, as compared to conventional such ball slides, and without having to increase the length of the sliding member, or having to shorten the lengths of the ball keepers or retainers.
A more specific object of this invention is to provide a ball slide having two sets of ball bearings mounted between the slide member and its associated base plate in such manner that upon movement of the slide member the ball bearings impart a differential amount of travel as between the moving member and the ball bearing retainers.
Other objects of the invention will be apparent hereinafter from the specification and from the recital of the appended claims, particularly when read in conjunction with the accompanying drawings.